JPMorgan has scheduled a conference call with investors and analysts for 6:15 p.m. PDT.

Separately, the Federal Deposit Insurance Corp. has announced a conference call with Chairwoman Sheila Bair for 6:30 p.m. PDT, without disclosing the topic. Speculation is that the government will announce that it will seize WaMu, paving the way for the deal.

New York-based JPMorgan has long been considered the most likely buyer of some or all of ailing WaMu, the nation’s largest thrift, with $182 billion in deposits.

The arrangement is expected to assure that the FDIC won't have to take a hit on WaMu's insured deposits.

JPMorgan has long coveted WaMu’s extensive branch network in California and Florida. It had offered to buy the Seattle-based thrift in spring, but WaMu instead accepted a $7 billion private equity investment from TPG, the former Texas Pacific Group.

WaMu put itself up for sale this month after its board ousted CEO Kerry Killinger.

The need for WaMu to strike a deal has become more urgent in recent days as the company’s debt rating was downgraded to deep-junk levels, and as its stock has plunged anew. The shares dived 57 cents, or 25%, to $1.69 today, the lowest since the 1980s.

It wasn’t clear what help the government might provide WaMu in dealing with its huge portfolio of troubled mortgages. Bad loans have forced the thrift to record $6.5 billion in losses over the past three quarters.

WaMu, or a successor bank, conceivably would benefit from the Bush administration’s proposed $700 billion bailout of the financial system, which would involve Treasury purchases of bad loans. But the debate over the bailout in Congress this week had given pause to several banks, including JPMorgan, that had been looking over WaMu’s books at the urging of the government, according to several sources who had been briefed on the matter.